Thanks for asking. When you see that error, it's best to ask for advice from the project, as you did. Different projects have different policies, and there are different situations that cause a profile to have a project box without a project account. The DD report gives the same generic instruction to every instance of the "error," but that suggestion is not applicable to every occurrence of that "error." Ask a human -- don't assume that a computer knows better.
In this instance, it looks like I was in hurry when I added the project boxes, and I forgot to go through the 4-step process to add the project account. I've added them now.